China reappointed veteran diplomat Wang Yi last week, replacing former rising star Qin Gang, who has not been seen for more than month.

Qin's unusually long and unexplained absence, his abruptly cut-short tenure, as well as other strange happenings like, mean speculation will continue to swirl.

Wang, known in Washington for his sharp intellect and his sometimes aggressive defence of China's positions, has been a fixture in US-China relations for years.